Industrial manufacturing faces many challenges in making consumer products faster, better and cheaper. As a result, manufacturers continuously explore the feasibility of assisting manual labor with automated tools. Such devices include, among others, computer controlled handling systems, which may pick and place parts in and out of process machines faster, more accurately and, therefore, increase the production throughput and the quality of the part.
While responding to market needs, manufacturers also need to make provisions for fast product changes on the same production line. While manual labor can easily adapt to such changes, automation tools must be physically reconfigured. Such reconfiguration results in down time, which in turn elongates the payback period of the tool.
In order to reduce down time, as result of tool changes, manufacturers are continuously searching for intelligent tools, which may be reconfigured upon controller command in a very short time and, therefore, quickly handle a need for a product change. Such a tool is sometimes referred to as an Intelligent End of Arm Tool (iEOAT).
iEOATs are gaining increased popularity among automotive manufacturers. This is because, in a typical automotive assembly line, exterior body parts, such as hoods, roofs, doors and wheels, can change from one car model to another. Such changes can involve changes in shape, color, size, texture. Accordingly, the tools that handle these parts must therefore change with it.
Automotive body parts are usually welded to each other in their manufacturing process. The body parts, which are being joined together are positioned along the assembly line in frames, fixtures or held by a robot while another robot moves in space to weld them. The need therefore is to have an intelligent tool at the end of the robot arm which will adapt to the changes in the body part. The iEOAT addresses this need by adding a higher level of intelligence and manipulation capabilities to capital equipment used in assembly lines.
In simple terms, the iEOAT may simply be a 3D adaptive gripper, which is mounted at the end of a robot arm, which carries locating pins and clamps. In the manufacturing process, the robot moves its arm at high acceleration in six degrees of freedom. The gripper at the end of the arm moves in close proximity with the car body part, and then moves slowly such that the pins locate the part. The gripper then closes its fingers around the body part and moves it quickly, once again, at high acceleration to the assembly point. The intelligent reconfigurable 3D gripper has the capability of adapting the location of its “pointing fingers” (pins) and “pinching fingers” (clamps) to the size and shape of the body part. However, since the shape of automotive body parts are three dimensional, the iEOAT must have the capability to adapt its finger's positions in three dimensions.
By using an iEOAT system in car manufacturing lines, automotive manufacturers may run small batch production on the same assembly line without the penalty of excessive downtime, which otherwise may be needed to change tools from one car model to the other.
However, conventional end of arm robot tools have one or more of the following limitations:
1. They consist of many accessory parts, like mounting brackets and support brackets, placing a burden on stocking many spare parts;
2. They lack standardization such that each tool requires custom design;
3. They are heavy, which limits the number of parts that the robot can carry;
4. They lack stiffness, which may damage motion components, reduce repeatability;
5. They are large, which limits the number of components which may mount on the robot;
6. They have “finger” motion, which is limited to one or two dimensions, which may limit the number of car models the robot may handle with the same tool;
7. Their stages have short travel of each finger which may limit the reach needed to handle a large number of car models;
8. They are custom made through a long engineering process consuming long setup time;
9. They are relatively expensive since their adaptability is to a limited number of car styles and they have to change with each new production line new car styles change.
Accordingly, it would be desirable to provide a universal end of arm robot tool that addresses all of the above drawbacks.